I'd say you're even selling yourself short Quarto, even though Poland fell rather quickly, with outdated equipment many more Germans were casaulties than expected, not to mention destroying 30% of their mechanized forces. Not only did it delay the invasion of France but also forced them to attack with significantly fewer medium tanks than planned, as the main attacks were forced to use lightly armed Panzer I and II's alongside III's not intended for that role.That's rather selling yourself short - the Netherlands, all things considered, put up an amazingly hard fight, even inflicting some local defeats on the Germans.
Much like the other armies in the world, the French still were using the armored tactics of WW1 where the tanks supported the infantry, unlike the Germans use of tanks as the spearhead and infantry for location control. Another factor was the organization of the army. In France at that point, divisions were assigned rigid areas to control which interferred with communication and supporting other units around them. In essence, very good men and equipment couldnt be used to their potential because of bad strategy.I realy doubt it was a lack of courage that caused the French defeat and the protraction of the war, but a fatal combination of wrong perception of the capabilities of the German Wehrmacht at the onset of the war in 1939 and outdated doctrines on the French part. Partly they probably were baffled by the success in the Polish campaign partly they were probably underestimating the Wehrmacht in their capabilities to perform a mechanized assault the way they did. And from what they knew in late 1939 and early 1940 a waiting stance to reinforce their positions and gear up their industries for a full scale war was probably the "right" decission to take. I doubt the average French soldier was that much less courageous than the average German or Dutch soldier, but he was thrust in a situation where fighting on seized to be a possibility after a certain point.